JPH1060209A - Aqueous solution oft polyvinyl alcohol having high thinxotropic property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject aqueous solution of a resin useful for a paper professing material, an adhesive, etc., excellent in thixotropic properties without damaging characteristics of a polyvinyl alcohol, comprising a polyvinyl alcohol- based resin and a specific polyarylic acid in a specific ratio. SOLUTION: This aqueous solution of a resin comprises (A) a polyvinyl alcohol-based resin, for example, having 300-500 polymerization degree and >=65mol% saponification degree and (B) a polyacrylic acid having >=1,000mPs.S viscosity of 1wt.% aqueous solution at 25 deg.C under 20rpm rotational speed by a Brookfield type viscometer as main components in the ratio of 0.1-100 pts.wt. of the component B to 100 pts.wt. of the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous solution of a polyvinyl alcohol resin having a high thixotropy.

[0002]

2. Description of the Related Art Polyvinyl alcohol (hereinafter abbreviated as PVA) resins are water-soluble, have excellent emulsifying / dispersing power and film-forming properties, and provide tough and flexible film properties. , Paper processing materials, adhesives, emulsifying and dispersing agents, ceramics, binders such as molds, mortar admixtures, mortar jointing materials, protective films, materials for forming molded products such as films, textile processing materials, cosmetic materials Used in a wide range of fields such as pharmaceutical materials. In these fields, the PVA-based resin is often mainly treated as a PVA aqueous solution, but it is well known that the PVA aqueous solution exhibits a viscosity characteristic close to Newtonian. However, in these fields of use, various viscosity characteristics are required, and therefore, PVA is used without deteriorating the characteristics of PVA, and in terms of ease of handling according to the application.
In many cases, the aqueous solution is required to have a viscous property having a large thixotropy different from the Newtonian viscosity property. However, at present, P having a thixotropic viscous property
There has been no method for obtaining a VA aqueous solution, and its use has sometimes been restricted.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a PVA aqueous solution having high thixotropy and viscous properties without impairing the properties of PVA.

[0004]

The PVA-based resin aqueous solution of the present invention achieves the above object, and the viscosity of a 1% by weight aqueous solution of PVA-based resin (A) at 25 ° C. is B
1000m under the condition of rotation speed 20rpm
A polyacrylic acid (B) having Pa · S or more as a main component, wherein the polyacrylic acid (B) is 0.1 to 100 parts by weight based on 100 parts by weight of the PVA-based resin (A). Is what you do.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The PVA resin used in the present invention may be any water-soluble resin and can be obtained by various known methods. For example, polymerization and saponification using a fatty acid vinyl ester such as vinyl formate, vinyl acetate or vinyl pivalate by a known method, or using vinyl ether such as t-butyl vinyl ether or benzyl vinyl ether It can be obtained by polymerization and hydrolysis by a known method. Industrially, a method of adding an alkali to a methanol solution of a polymer obtained by solution polymerization of vinyl acetate, mixing, and saponifying is advantageous. At this time, depending on the application, carboxyl group, anionic or ammonium salt such as sulfone group, cationic ionic group such as amino group, ethylene group, propylene group, lauryl group, hydrophobic group such as stearyl group, silicon-containing group, Modified PVA in which one or more functional groups such as a fluorine-containing group, a thiol group, a diketene group, an epoxy group, and a halogen group are introduced into a main chain, a side chain, and a terminal of a molecule by a known technique.
But it doesn't matter. The degree of polymerization and the degree of saponification of the PVA-based resin may be of various types.
0 to 3500, and a saponification degree of 65 mol% or more.

The polyacrylic acid used in the present invention is polyacrylic acid, an alkali salt thereof, or the like, and one or more of these may be used in combination. It may be 1000 mPa · S or more at a rotational speed of 20 rpm. When the viscosity of a 1% by weight aqueous solution of polyacrylic acid at 25 ° C. is less than 1000 mPa · S under the condition of 20 rpm using a B-type viscometer, P having a high thixotropic viscosity is used.
It becomes difficult to obtain a VA-based aqueous solution.

The polyacrylic acid used in the present invention is preferably a crosslinked polyacrylic acid and / or an alkali salt thereof. As the alkali used as the alkali salt, various alkalis are used, and examples thereof include sodium hydroxide, potassium hydroxide, and ammonia. Usually, sodium hydroxide is often used.

[0008] The use ratio of polyacrylic acid is PV
The amount is 0.1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the A-based resin. Here, 0.
If the amount is less than 1 part by weight, it is difficult to obtain a PVA-based aqueous solution having a high thixotropic viscosity. Also, 1
If the amount exceeds 00 parts by weight, the film properties of the obtained PVA-based resin will be impaired.

The thixotropy of the PVA-based aqueous solution of the present invention is determined by using a B-type viscometer at 10 rpm at 30 ° C.
Viscosity ratio measured at a rotation speed of 00 rpm (η 10 rpm / η
100 rpm) is preferably 1.5 to 10. If the thixotropy of the PVA-based aqueous solution is too small, the PVA-based aqueous solution may penetrate too much when applied to a porous substrate such as paper or cloth, or the PVA-based aqueous solution may be cast when applied thickly. There is a possibility that the effect of the present invention may not be able to be exhibited. In addition, if the thixotropic property of the PVA-based aqueous solution is too large, it is difficult to uniformly coat.

The method for producing a PVA-based aqueous solution of the present invention
The VA-based resin (A) and the polyacrylic acid (B) are the main components, and (B) is 0.1 to 10 parts by weight based on 100 parts by weight of (A).
Any production method may be used as long as an aqueous solution of 0 parts by weight can be obtained. For example, a method in which a mixture of (A) and (B) is added to water and dissolved by heating, and a method in which aqueous solutions in which (A) and (B) are separately dissolved can be exemplified. In addition, as a preparation method when an alkali salt of polyacrylic acid is used at that time, the polyacrylic acid may be preliminarily converted into an alkali salt before being added to water, and together with the addition of polyacrylic acid, An alkali may be added, or a predetermined amount of alkali may be added after the addition of polyacrylic acid.

The total concentration of the PVA-based resin and the polyacrylic acid in the aqueous PVA-based solution of the present invention may be various, but is usually used at 0.5 to 30% by weight.

The PVA-based aqueous solution of the present invention may contain, if necessary, an antifoaming agent, a wetting agent,
Fungicide, deicing agent, surfactant, plasticizer for PVA, P
A water-resistant agent of VA, a water-soluble natural resin other than PVA and polyacrylic acid, or a synthetic resin can also be used in combination.

The PVA-based aqueous solution of the present invention has a high thixotropic viscosity without impairing the properties of PVA.
Aqueous solution, paper processing materials, adhesives, emulsifying and dispersing agents,
Ceramics, binders such as molds, mortar admixtures,
It is useful in a wide range of fields such as a material for forming a molded product such as a mortar joint material, a protective film and a film, a fiber processing material, a cosmetic material, and a pharmaceutical material.

[0014]

The present invention will be described in detail below with reference to examples and comparative examples. Here, physical properties in Examples and Comparative Examples are measured by the following methods unless otherwise specified.

[0015] The thixotropy of the obtained PVA-based aqueous solution was measured using a B-type viscometer at a rotation speed of 10 r at 30 ° C.
The viscosity was measured under the conditions of pm and 100 rpm, and the ratio was evaluated. . The film properties are as follows: strength and elongation (20 ° C.,
(Under 65% RH).

(Example 1) Degree of polymerization: 2,000, degree of saponification: 8
8.4 mol% of PVA and sodium hydroxide salt of Hibiswaco-304 (manufactured by Wako Pure Chemical Industries, Ltd.) as polyacrylic acid (viscosity of a 1% by weight aqueous solution at 25 ° C. is 20 rpm using a B-type viscometer. 12000 under measurement conditions
(0 mPa · S) was heated and dissolved in water to prepare a 2% by weight aqueous solution. The viscosity of this aqueous solution is 13000 mPa · S at 10 rpm, 1
4200 mPa · S at 00 rpm, and 10 rpm /
The viscosity ratio at 100 rpm was 3.1, indicating a high thixotropic property. The strength of the obtained film is 400 kg / cm,
The elongation was 130%, which was good.

(Example 2) Degree of polymerization 1700, degree of saponification 9
Sodium hydroxide salt of 8.4 mol% of PVA and Hibiswaco-105 (manufactured by Wako Pure Chemical Industries, Ltd.) as polyacrylic acid (the viscosity of a 1% by weight aqueous solution at 25 ° C. is 12000 mPa · s at 20 rpm using a B-type viscometer). S) was dissolved in water by heating to prepare a 2% by weight aqueous solution. The viscosity of this aqueous solution is 10 rpm
m at 23000mPa · S, 100rpm at 5000m
Pa · S, and the viscosity ratio of 10 rpm / 100 rpm was 4.6, indicating a high thixotropic property. The strength of the obtained film was 430 kg / cm and the elongation was 60%, which was good.

(Example 3) Degree of polymerization: 1700, degree of saponification: 9
The weight ratio of 8.4 mol% of PVA to the sodium hydroxide salt of Hibiswaco-105 as polyacrylic acid is 99%.
/ 1 was heated and dissolved in water to prepare a 2% by weight aqueous solution. The viscosity of this aqueous solution is 9000 mP at 10 rpm.
a · S, 1800 mPa · S at 100 rpm, 1
The viscosity ratio of 0 rpm / 100 rpm was 5.0, indicating a high thixotropic property. The strength of the obtained film is 420k
g / cm and elongation were 300%, which were favorable.

(Example 4) Degree of polymerization 1700, degree of saponification 9
8.4 mol% of PVA and Hibiswaco-105 as polyacrylic acid (the viscosity of a 1% by weight aqueous solution at 25 ° C. is 2100 mPa · S at 20 rpm using a B-type viscometer).
Was heated and dissolved in water to prepare a 2% by weight aqueous solution. The viscosity of this aqueous solution is 12000 mPa · S at 10 rpm, and 100 rpm.
And the viscosity ratio at 2100 mPa · S, 10 rpm / 100 rpm was 5.7, indicating a high thixotropic property.
The strength of the obtained film is 410 kg / cm and the elongation is 100
%Met.

(Comparative Example 1) Degree of polymerization 1700, degree of saponification 9
8.4 mol% of PVA was heated and dissolved in water to prepare a 10 wt% aqueous solution. The viscosity of this aqueous solution is 950 mPa · S at 10 rpm, 930 mPa · S at 100 rpm, and the viscosity ratio of 10 rpm / 100 rpm is 1.0.
It had a small thixotropy. The obtained film had a strength of 450 kg / cm and an elongation of 350%.

Comparative Example 2 Degree of polymerization: 1700, Degree of saponification: 9
The weight ratio of 8.4 mol% of PVA to the sodium hydroxide salt of Hibiswaco-105 as polyacrylic acid is 40.
/ 60 was heated and dissolved in water to prepare a 2% by weight aqueous solution. The viscosity of this aqueous solution is 28,000 at 10 rpm.
mPa · S, 5500 mPa · S at 100 rpm, viscosity ratio of 10 rpm / 100 rpm: 5.1, high thixotropy, strength of obtained film: 48
Although it was 0 kg / cm, the elongation of the film was 5%, and it was a very brittle film.

[0022]

As is apparent from the above description, according to the present invention, it is possible to provide a PVA aqueous solution having a high thixotropic viscous property while retaining excellent properties of PVA without impairing it. became.

Claims (1)

[Claims] 1. Polyvinyl alcohol resin (A) and 2
A 1% by weight aqueous solution at 5 ° C. is mainly composed of polyacrylic acid (B) having a viscosity of not less than 1000 mPa · S at a rotation speed of 20 rpm with a B-type viscometer, and 100 weight parts of a polyvinyl alcohol resin (A) An aqueous solution of a polyvinyl alcohol-based resin, wherein the amount of the polyacrylic acid (B) is 0.1 to 100 parts by weight per part by weight.